Voice coil motor and lens barrel

Abstract

To provide a small-sized voice coil motor, the voice coil motor includes a first yoke and a second yoke each having a length in a first direction, a third yoke that has a length in the first direction and is disposed between the first yoke and the second yoke, a first magnet disposed on the first yoke, a second magnet disposed on the second yoke, and a coil that is penetrated by the third yoke and is movable in the first direction by magnetic forces of the first magnet and the second magnet, wherein the coil includes a first section in which a winding wire is linearly wound and a second section in which the wiring wire is wound in an arc shape.

The invention claimed is: 
     
         1 . A voice coil motor comprising:
 a first yoke and a second yoke each having a length in a first direction;   a third yoke that has a length in the first direction and is disposed between the first yoke and the second yoke;   a first magnet disposed on the first yoke;   a second magnet disposed on the second yoke; and   a coil that is penetrated by the third yoke and is movable in the first direction by magnetic forces of the first magnet and the second magnet,   wherein the coil includes a first section in which a winding wire is linearly wound and a second section in which the wiring wire is wound in an arc shape,   wherein the first yoke and the second yoke each have a rectangular shape when viewed from the first direction, and   wherein a diameter of a virtual cylinder whose outer peripheral surface coincides with a part of an outer peripheral surface of the third yoke is larger than a length in a longitudinal direction of the rectangular shape.   
     
     
         2 . The voice coil motor according to  claim 1 , wherein the second section faces the first section with the third yoke interposed therebetween. 
     
     
         3 . The voice coil motor according to  claim 1 , wherein the coil has a substantially D-shape when viewed from the first direction. 
     
     
         4 . The voice coil motor according to  claim 1 , wherein a surface of the third yoke facing the first section is substantially parallel to the first section. 
     
     
         5 . The voice coil motor according to  claim 1 , wherein a cross point at which winding wires of the coil cross each other is located in the first section. 
     
     
         6 . The voice coil motor according to  claim 1 ,
 wherein a first plane including a first side surface, which faces the first magnet, of the first yoke intersects with a second plane including a second side surface, which faces the second magnet, of the second yoke, and   wherein the third yoke is located between an intersection line between the first plane and the second plane and the first section of the coil.   
     
     
         7 . The voice coil motor according to  claim 1 , further comprising:
 a fourth yoke connecting first ends of the first yoke, the second yoke, and the third yoke in the first direction; and   a fifth yoke connecting second ends of the first yoke, the second yoke, and the third yoke in the first direction,   wherein the first yoke, the second yoke, and the fifth yoke are integrally formed by one member.   
     
     
         8 . The voice coil motor according to  claim 7 , wherein in the first direction, a distance between the fourth yoke and the first magnet and a distance between the fourth yoke and the second magnet are shorter than a distance between the fifth yoke and the first magnet and a distance between the fifth yoke and the second magnet. 
     
     
         9 . The voice coil motor according to  claim 7 ,
 wherein the third yoke has protruding portions on respective end surfaces of the third yoke in the first direction, and   wherein the fourth yoke and the fifth yoke include engagement portions that engage with the protruding portions, respectively.   
     
     
         10 . A lens barrel comprising the voice coil motor according to  claim 1 . 
     
     
         11 . The lens barrel according to  claim 10 , further comprising:
 a lens; and   a lens holding frame that holds the lens and is connected to the coil,   wherein the voice coil motor is disposed so that the first direction is parallel to an optical axis of the lens, and   wherein the third yoke is located between the first section of the coil and the lens in a radial direction of the lens.   
     
     
         12 . A voice coil motor comprising:
 a first yoke and a second yoke each having a length in a first direction;   a third yoke that has a length in the first direction and is disposed between the first yoke and the second yoke;   a first magnet disposed on the first yoke;   a second magnet disposed on the second yoke; and   a coil that is penetrated by the third yoke and is movable in the first direction by magnetic forces of the first magnet and the second magnet,   wherein the coil includes a first section in which a winding wire is linearly wound and a second section in which the wiring wire is wound in an arc shape, and   wherein a cross point at which winding wires of the coil cross each other is located in the first section.   
     
     
         13 . The voice coil motor according to  claim 12 , wherein the second section faces the first section with the third yoke interposed therebetween. 
     
     
         14 . The voice coil motor according to  claim 12 , wherein the coil has a substantially D-shape when viewed from the first direction. 
     
     
         15 . The voice coil motor according to  claim 12 , wherein a surface of the third yoke facing the first section is substantially parallel to the first section. 
     
     
         16 . The voice coil motor according to  claim 12 ,
 wherein a first plane including a first side surface, which faces the first magnet, of the first yoke intersects with a second plane including a second side surface, which faces the second magnet, of the second yoke, and   wherein the third yoke is located between an intersection line between the first plane and the second plane and the first section of the coil.   
     
     
         17 . A lens barrel comprising the voice coil motor according to  claim 13 . 
     
     
         18 . A voice coil motor comprising:
 a first yoke and a second yoke each having a length in a first direction;   a third yoke that has a length in the first direction and is disposed between the first yoke and the second yoke;   a fourth yoke connecting first ends of the first yoke, the second yoke, and the third yoke in the first direction;   a fifth yoke connecting second ends of the first yoke, the second yoke, and the third yoke in the first direction,   a first magnet disposed on the first yoke;   a second magnet disposed on the second yoke; and   a coil that is penetrated by the third yoke and is movable in the first direction by magnetic forces of the first magnet and the second magnet,   wherein the coil includes a first section in which a winding wire is linearly wound and a second section in which the wiring wire is wound in an arc shape, and   wherein the first yoke, the second yoke, and the fifth yoke are integrally formed by one member.   
     
     
         19 . The voice coil motor according to  claim 18 , wherein in the first direction, a distance between the fourth yoke and the first magnet and a distance between the fourth yoke and the second magnet are shorter than a distance between the fifth yoke and the first magnet and a distance between the fifth yoke and the second magnet. 
     
     
         20 . The voice coil motor according to  claim 18 ,
 wherein the third yoke has protruding portions on respective end surfaces of the third yoke in the first direction, and   wherein the fourth yoke and the fifth yoke include engagement portions that engage with the protruding portions, respectively.